Conventional cooktops are known to include a grill portion and a range top portion. Typically, the cooktop can include gas or electric burners and a grill element, along with associated controls. Some cooktops further include a downdraft feature whereby a downdraft fan pulls cooking odors and grease laden air downwardly through a grate in the cooktop and moves it, through ducting, from the kitchen to outside the home.
Typically the downdraft fans are multiple speed fans, having a low speed and a high speed. The fans are generally controlled by a multi-position switch or a potentiometer or rheostat to set the speed of the fan. For removal of normal cooking odors or steam or the like, low speed operation of the downdraft fan is typically adequate. However, when using the grill portion, a fan set at low speed has been unable to withdraw all of the grease laden air from the kitchen and duct it to the outside environment. In particular, experience has shown that a downdraft fan must move about 300 cubic feet of air per minute (cfm) in order to avoid grease accumulation in the ducting. At slower speeds, grease can accumulate, especially at elbows formed in the ducting. Eventually, the grease accumulation can begin to close off and restrict the air flow through the ducting, thereby reducing the effectiveness of the air removal fans, and cause other problems as well. Unfortunately, a cook can forget to set the fan at high speed. In some cases, the cook may intentionally operate the fan at low speed during grill operation, such as when a lower noise level may be desirable. Accordingly, it is desirable that a downdraft fan is always operated at high speed during grill operation regardless of the cook's selected operation of the fan.